Infrared gas sensor

Abstract

The utility model relates to an infrared gas sensor. The infrared gas sensor comprises a shell, a fixing plate and a mounting plate, wherein a first plane, a first reflecting surface, a second reflecting surface and a first arc surface are arranged in the shell. And an infrared light source and an infrared detector are arranged on the mounting plate. The fixing plate is provided with a first through hole and a second through hole. An arc-shaped plate is arranged in the optical cavity in the shell, the arc-shaped plate is provided with a second arc surface, an optical gas cavity is formed between the first arc surface and the second arc surface, and a vent hole communicated with the optical gas cavity is formed in the shell. Light of the infrared light source can be reflected to the first arc surface through the first reflecting surface, reflected to the second arc surface through the first arc surface, reflected to the first arc surface through the second arc surface, reflected to the second reflecting surface through the first arc surface, and reflected to the infrared detector through the second reflecting surface. Compared with the prior art, the optical path is increased, the detection precision of the sensor is improved, the volume of the air chamber is reduced, and the response time is shortened.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of infrared gas sensors, and specifically relates to a kind of infrared gas sensors. BACKGROUND

[0002] Infrared gas sensor is a kind of gas sensing device based on the near-infrared spectrum selective absorption characteristics of different gas molecules, using gas concentration and absorption intensity relationship (Lambert-Beer law) to identify gas components and determine its concentration. Its application range is very wide, and it is used in detecting many kinds of gas. Compared with other categories of gas sensors such as electrochemical type, catalytic combustion type, semiconductor type, etc., it has a series of advantages such as long service life, high sensitivity, good stability, suitable for many gases, high cost performance, low maintenance cost, online analysis, etc. It is widely used in petrochemical industry, metallurgical industry, mining exploration, air pollution detection, agriculture, medical health and other fields.

[0003] The existing infrared gas sensor, such as the Chinese utility model patent with the authorized announcement number CN 215066148 U, discloses an infrared gas sensor, which includes a shell, a fixed plate and a mounting plate. The shell is internally provided with a first plane, a circular arc surface, a first reflecting surface, a second reflecting surface and a ventilation hole. An infrared light source and an infrared detector are arranged on the mounting plate. The fixed plate is provided with a first through hole and a second through hole. An optical cavity (i.e. a gas chamber) is formed between the fixed plate and the shell. The light of the infrared light source is reflected by the first reflecting surface to the circular arc surface, and then reflected to the second reflecting surface and the infrared detector. However, this structure of infrared gas sensor still has the following technical problems: the light path reflection length of the light of the infrared light source is short, and the detection precision is low; in addition, the gas chamber has large volume, and the time spent for gas filling is long, and the response time is long. CONTENT OF THE UTILITY MODEL

[0004] The utility model aims to provide an infrared gas sensor to solve the problems of low detection precision and long response time in the prior art.

[0005] In order to achieve the above object, the utility model discloses an infrared gas sensor adopts the following technical scheme: an infrared gas sensor, including the casing, fixed plate and mounting plate, be provided with first plane, first reflection surface, second reflection surface and first circular arc surface in the casing, be provided with infrared light source and infrared detector on the mounting plate, be provided with the first through hole for the corresponding installation of infrared light source and the second through hole for the corresponding installation of infrared detector on the fixed plate, and the fixed plate is located in the casing and is in abutment with first plane, be provided with arc plate in the optical cavity in the casing, and the arc plate has second circular arc surface that is provided with opposite first circular arc surface, and the optical gas cavity is formed between first circular arc surface and second circular arc surface, be provided with the vent hole that communicates with the optical gas cavity on the casing, and the light of infrared light source can be reflected to first circular arc surface through first reflection surface, is reflected to second circular arc surface through first circular arc surface, is reflected to first circular arc surface again through second circular arc surface, is reflected to second reflection surface again through first circular arc surface, and is reflected to infrared detector through second reflection surface.

[0006] The number of vent holes is multiple and is arranged on the casing in a circumferential direction.

[0007] The light of the infrared light source is reflected at least six times between the first circular arc surface and the second circular arc surface.

[0008] The first circular arc surface and the second circular arc surface are concentrically arranged.

[0009] The first reflection surface, the first circular arc surface, the second circular arc surface and the second reflection surface are all provided with a metal plating layer for improving light reflection.

[0010] The first reflection surface is a parabolic surface, and the emission point of the infrared light source coincides with the focal point of the parabolic surface to improve the intensity of the reflected light.

[0011] The second reflection surface is an inclined surface, and the second reflection surface forms an angle of 40-50° with the first plane, so that the light reaching the second reflection surface can be reflected to the infrared detector.

[0012] The casing is made of plastic, and / or the fixed plate is made of plastic.

[0013] The mounting plate is provided with a temperature sensor, the fixed plate is provided with a third through hole for the corresponding installation of the temperature sensor, and the casing is provided with a fourth through hole corresponding to the third through hole.

[0014] The temperature sensor is located at the center of the mounting plate, and the distance between the infrared light source and the temperature sensor is equal to the distance between the infrared detector and the temperature sensor support.

[0015] The utility model discloses a beneficial effect: set up arc plate in the shell interior, the second arc surface of arc plate and the first arc surface form optical gas cavity, this compares with prior art, effectively reduced the volume of gas cavity, accelerated the target gas's filling and discharging speed, reduced response time. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a structure schematic diagram of an embodiment of the infrared gas sensor of the utility model;

[0017] Figure 2 It is Figure 1 It is a structure schematic diagram under another angle;

[0018] Figure 3 It is Figure 1 It is the internal structure schematic diagram of the middle shell;

[0019] Figure 4 It is Figure 1 It is the light path schematic diagram of light. DETAILED DESCRIPTION

[0020] In order to facilitate understanding the utility model, below combining with the specific embodiment, the utility model is carried out more detailed explanation. The preferred embodiment of the utility model is given in the drawing. However, the utility model can be realized in many different forms, and is not limited to the embodiment described in this specification. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the utility model more thorough and comprehensive.

[0021] It should be noted that, unless otherwise defined, the technical and scientific terms used in this specification are the same as the meanings understood by the person skilled in the art belonging to the technical field of the utility model. The technical and scientific terms used in the specification of the utility model are only for the purpose of describing the specific embodiments, and are not used to limit the utility model.

[0022] The embodiment of the infrared gas sensor of the utility model, such as Figures 1-4As shown, it comprises a shell 1, a fixed plate 2 and a mounting plate 3. The shell 1 is provided with a first plane 13, a second plane 19, a first reflecting surface 14, a second reflecting surface 15 and a first circular arc surface 16. The first plane 13 and the second plane 19 are of different heights and form a stepped surface. This part belongs to the prior art. In this embodiment, the shell 1 is provided with an arc-shaped plate 17, which has a second circular arc surface 18 arranged opposite to the first circular arc surface 16. The first circular arc surface 16 and the second circular arc surface 18 form an optical gas cavity 22. The shell is provided with a plurality of air holes 4 which communicate with the optical gas cavity. The air holes 4 are arranged on the shell in a circumferential direction. In this embodiment, the number of air holes is 13 and they are arranged in the arc direction of the optical gas cavity. The target gas enters the optical gas cavity through the air holes. In other embodiments, the number and position of the air holes can be adjusted according to actual needs. In this embodiment, the shell 1 is made of plastic and the fixed plate 2 is also made of plastic. In other embodiments, the shell and the fixed plate can both be made of metal, or one of them is made of plastic and the other is made of metal.

[0023] The mounting plate 3 is provided with an infrared light source 10, an infrared detector 11 and a temperature sensor 12. The temperature sensor 12 is located at the center of the mounting plate 2. The distance between the infrared light source 10 and the temperature sensor 12 is equal to the distance between the infrared detector 11 and the temperature sensor 12. This arrangement allows the temperature sensor to be tested at the center, making the measured temperature more representative. Moreover, the light path exists in the circumferential direction of the temperature sensor, so that the detected temperature point is in the center of the light path, and the measured temperature is more accurate relative to the entire light path. The fixed plate 2 is provided with a first through hole 6 for mounting the infrared light source 10, a second through hole 7 for mounting the infrared detector 11 and a third through hole 8 for mounting the temperature sensor 12. The shell 1 is provided with a fourth through hole 5 corresponding to the third through hole 8. The first through hole 6, the second through hole 7 and the third through hole 8 are each provided with a flange 20 on the side close to the mounting plate. This arrangement increases the length of the first through hole, the second through hole and the third through hole, increases the support area provided, and improves the stability of the infrared light source, the infrared detector and the temperature sensor. On the other hand, the position of the through hole of the fixed plate has a larger thickness, and the part of the fixed plate without the through hole has a smaller thickness. This also increases the space between the fixed plate and the mounting plate to some extent, thereby providing more space for the mounting plate to mount electronic components.

[0024] The fixed plate 2 is located in the shell and abuts against the first plane 13, and a positioning installation structure is arranged therebetween. The positioning installation structure comprises a limiting protrusion 21 arranged on the inner wall of the shell and a limiting groove 9 arranged on the fixed plate, and cooperation of the limiting protrusion and the limiting groove can improve assembly efficiency. In addition, the shell is provided with the limiting protrusion, so that the wall thickness of the shell is increased, and the strength of the shell is improved. In other embodiments, the limiting groove can also be arranged on the shell, and the limiting protrusion is arranged on the fixed plate, wherein the limiting groove is arranged on the shell, so that the first plane of the shell is convenient for processing by using a milling cutter, and the processing process does not need to avoid the limiting component, and the processing efficiency is improved. The gap between the shell, the fixed plate and the mounting plate is provided with sealing glue, and the gap between the infrared light source and the first through hole, the gap between the infrared detector and the second through hole and the gap between the temperature sensor and the third through hole are all provided with sealing glue. This arrangement seals each mounting gap, avoids the influence of the non-detection end on the light path cavity, and improves detection accuracy.

[0025] In the embodiment, the light of the infrared light source is reflected at least six times between the first circular arc surface 16 and the second circular arc surface 18. In the embodiment, the number of reflections between the two is 6 times, and in other embodiments, it can also be adjusted as needed. The first circular arc surface 16 and the second circular arc surface 18 are concentrically arranged. In other embodiments, the first circular arc surface and the second circular arc surface can also be arranged eccentrically, as long as the reflection of the light between the two is not less than six times. The first reflecting surface 14, the first circular arc surface 16, the second circular arc surface 18 and the second reflecting surface 15 are all provided with a metal plating layer for improving light reflection. In the embodiment, the metal plating layer is a gold plating layer, and in other embodiments, other metals such as a silver plating layer can also be used. The first reflecting surface 14 is a parabolic surface, and the emission point of the infrared light source coincides with the focal point of the parabolic surface, which can improve the intensity of the reflected light. The second reflecting surface 15 is an inclined surface, and the second reflecting surface forms an angle of 40-50° with the first plane, and the best choice is 45°, so that the light reaching the second reflecting surface can be reflected by 90 degrees to the infrared detector. In other embodiments, the angle of the second reflecting surface can be adjusted as needed, for example, 40 degrees or 50 degrees, as long as the light reaching the second reflecting surface can be reflected to the infrared detector.

[0026] In use, the light emitted by the infrared light source can be reflected by the first reflecting surface to the first circular arc surface, reflected by the first circular arc surface to the second circular arc surface, and reflected by the second circular arc surface to the first circular arc surface again. The light is reflected between the first circular arc surface and the second circular arc surface for multiple times, reaches the second reflecting surface, and is reflected by the second reflecting surface to the infrared detector. The fixed plate does not participate in the reflection, and therefore, only the accuracy of the shell needs to be ensured during processing. The optical gas cavity is formed between the first circular arc surface and the second circular arc surface, which can effectively reduce the volume of the gas cavity, accelerate the charging and discharging speed of the target gas, and reduce the response time. The second circular arc surface is arranged, so that the light of the infrared light source is reflected between the first circular arc surface and the second circular arc surface for multiple times before reaching the second reflecting surface, the reflection distance is increased, and the detection accuracy is improved.

[0027] In the above description of the present specification, unless otherwise explicitly specified and limited, the terms "fixed", "mounted", "connected" or "linked" and the like should be understood in a broad sense. For example, as to the term "connected", it can be fixed connection, detachable connection, or integral; it can be mechanical connection, electrical connection; it can be direct connection, indirect connection through an intermediate medium, or internal connection of two elements or interaction relationship between two elements. Therefore, unless otherwise explicitly limited in the present specification, the above terms can be understood in the specific meaning in the present application by the person skilled in the art according to the specific circumstances.

[0028] According to the above description of the present specification, the person skilled in the art can also understand the terms used as follows, for example, the terms indicating the orientation or positional relationship such as "upper", "lower", "front", "rear", "left", "right", "length", "width", "thickness", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", "center", "longitudinal", "transverse", "clockwise" or "counterclockwise" are based on the orientation or positional relationship shown in the drawings of the present specification, which is only for the purpose of facilitating the description of the scheme of the present application and simplifying the description, and does not explicitly or implicitly indicate or suggest that the devices or elements involved must have the specific orientation, be constructed and operated in the specific orientation, therefore the above orientation or positional relationship terms cannot be understood or interpreted as a limitation on the scheme of the present application.

[0029] In addition, the terms "first" or "second" and the like used in the present specification are terms used to refer to numbers or ordinal numbers only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first" or "second" can explicitly or implicitly include at least one of the features. In the description of the present specification, the meaning of "plurality" is at least two, for example, two, three or more, etc., unless otherwise explicitly specified and limited.

Claims

1. An infrared gas sensor comprising a housing, a fixing plate and a mounting plate, the housing is provided with a first plane, a first reflecting surface, a second reflecting surface and a first circular arc surface, the mounting plate is provided with an infrared light source and an infrared detector, the fixing plate is provided with a first through hole for corresponding installation of the infrared light source and a second through hole for corresponding installation of the infrared detector, the fixing plate is located in the housing and abuts against the first plane, characterized in that: The arc-shaped plate is arranged in the optical cavity in the shell, and has a second circular arc surface arranged opposite to a first circular arc surface, and an optical gas cavity is formed between the first circular arc surface and the second circular arc surface; the shell is provided with a vent hole in communication with the optical gas cavity; the light of the infrared light source is reflected to the first circular arc surface through the first reflecting surface, reflected to the second circular arc surface through the first circular arc surface, reflected to the first circular arc surface again through the second circular arc surface, reflected to the second reflecting surface through the first circular arc surface again, and reflected to the infrared detector through the second reflecting surface.

2. The infrared gas sensor of claim 1, wherein: The number of the vent holes is multiple, and the vent holes are arranged on the shell in a circumferential direction.

3. The infrared gas sensor of claim 1, wherein: The light of the infrared light source is reflected between the first circular arc surface and the second circular arc surface for at least six times.

4. The infrared gas sensor of claim 1, wherein: The first circular arc surface and the second circular arc surface are concentrically arranged.

5. The infrared gas sensor of claim 1, wherein: Metallic plating layers for improving light reflection are arranged on the first reflecting surface, the first circular arc surface, the second circular arc surface and the second reflecting surface.

6. The infrared gas sensor of claim 1, wherein: The first reflecting surface is a parabolic surface, and the emission point of the infrared light source coincides with the focal point of the parabolic surface, so as to improve the intensity of the reflected light.

7. The infrared gas sensor of claim 1, wherein: The second reflecting surface is an inclined surface, and the second reflecting surface forms an angle of 40-50° with the first plane, so that the light reaching the second reflecting surface can be reflected to the infrared detector.

8. The infrared gas sensor of claim 1, wherein: The shell is made of plastic, and / or the fixing plate is made of plastic.

9. The infrared gas sensor according to any one of claims 1 to 8, characterized in that: A temperature sensor is arranged on the mounting plate, a third through hole for corresponding installation of the temperature sensor is arranged on the fixing plate, and a fourth through hole corresponding to the third through hole is arranged on the shell.

10. The infrared gas sensor of claim 9, wherein: The temperature sensor is located at the center of the mounting plate, and the distance between the infrared light source and the temperature sensor is equal to the distance between the infrared detector and the temperature sensor support.

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